Jim, I tried as you suggested and my performance dropped by 50%. I went from a 32 TPS to 16. Oh well. Steve On Wed, 2006-08-09 at 16:05 -0500, Jim C. Nasby wrote: > On Tue, Aug 08, 2006 at 10:45:07PM -0700, Steve Poe wrote: > > Luke, > > > > I thought so. In my test, I tried to be fair/equal since my Sun box has two > > 4-disc arrays each on their own channel. So, I just used one of them which > > should be a little slower than the 6-disc with 192MB cache. > > > > Incidently, the two internal SCSI drives, which are on the 6i adapter, > > generated a TPS of 18. > > You should try putting pg_xlog on the 6 drive array with the data. My > (limited) experience with such a config is that on a good controller > with writeback caching enabled it won't hurt you, and if the internal > drives aren't caching writes it'll probably help you a lot. > > > I thought this server would impressive from notes I've read in the group. > > This is why I thought I might be doing something wrong. I stumped which way > > to take this. There is no obvious fault but something isn't right. > > > > Steve > > > > On 8/8/06, Luke Lonergan <LLonergan@xxxxxxxxxxxxx> wrote: > > > > > >Steve, > > > > > >> Sun box with 4-disc array (4GB RAM. 4 167GB 10K SCSI RAID10 > > >> LSI MegaRAID 128MB). This is after 8 runs. > > >> > > >> dbserver-dual-opteron-centos,08/08/06,Tuesday,20,us,12,2,5 > > >> dbserver-dual-opteron-centos,08/08/06,Tuesday,20,sy,59,50,53 > > >> dbserver-dual-opteron-centos,08/08/06,Tuesday,20,wa,1,0,0 > > >> dbserver-dual-opteron-centos,08/08/06,Tuesday,20,id,45,26,38 > > >> > > >> Average TPS is 75 > > >> > > >> HP box with 8GB RAM. six disc array RAID10 on SmartArray 642 > > >> with 192MB RAM. After 8 runs, I see: > > >> > > >> intown-vetstar-amd64,08/09/06,Tuesday,23,us,31,0,3 > > >> intown-vetstar-amd64,08/09/06,Tuesday,23,sy,16,0,1 > > >> intown-vetstar-amd64,08/09/06,Tuesday,23,wa,99,6,50 > > >> intown-vetstar-amd64,08/09/06,Tuesday,23,id,78,0,42 > > >> > > >> Average TPS is 31. > > > > > >Note that the I/O wait (wa) on the HP box high, low and average are all > > >*much* higher than on the Sun box. The average I/O wait was 50% of one > > >CPU, which is huge. By comparison there was virtually no I/O wait on > > >the Sun machine. > > > > > >This is indicating that your HP machine is indeed I/O bound and > > >furthermore is tying up a PG process waiting for the disk to return. > > > > > >- Luke > > > > > > >
